How do you get Valgrind to show line errors?

Question

How do you get Valgrind to show exactly where an error occured? I compiled my program (on a Windows machine over a Linux terminal via PuTTy) adding the -g debug option.

When I run Valgrind, I get the Leak and Heap summary, and I definitely have lost memory, but I never get information about where it happens (file name, line). Shouldn't Valgrind be telling me on what line after I allocate memory, it fails to deallocate later?

==15746==
==15746== HEAP SUMMARY:
==15746==     in use at exit: 54 bytes in 6 blocks
==15746==   total heap usage: 295 allocs, 289 frees, 11,029 bytes allocated
==15746==
==15746== LEAK SUMMARY:
==15746==    definitely lost: 12 bytes in 3 blocks
==15746==    indirectly lost: 42 bytes in 3 blocks
==15746==      possibly lost: 0 bytes in 0 blocks
==15746==    still reachable: 0 bytes in 0 blocks
==15746==         suppressed: 0 bytes in 0 blocks
==15746== Rerun with --leak-check=full to see details of leaked memory
==15746==
==15746== For counts of detected and suppressed errors, rerun with: -v
==15746== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 15 from 8)

Answer 1

Try valgrind --leak-check=full

This normally prints more useful information. Also add the -O0 flag when compiling so your code doesn't get optimized.

Answer 2

I've repeatedly gotten hosed on this, and couldn't figure out why '--leak-check=full' wasn't working for me, so I thought I'd bump up tune2fs comment.

The most likely problem is that you've (Not ShrimpCrackers, but whoever is reading this post right now) placed --leak-check=full at the end of your command line. Valgrind would like you to post the flag before you enter the actual command line to run your program.

i.e.:

valgrind --leak-check=full ./myprogram

NOT:

valgrind ./myprogram --leak-check=full

Answer 3

Let me be more specific for other readers (i had the same problem but my arguments were in the right order): I found out that valgrind needs the path to the executable, if you dont give this then it will run bu it won't give you the line numbers. In my case the executable was in a different directory, which was in my PATH, but to get the line information you have to run

valgrind --leak-check=full path_to_myprogram/myprogram